I understand that the browser displays above all other controls regardless of its layer number.
Does that mean you cannot have more than one (non-overlapping) browser widgets on a card?

I am having problems with two browser widgets on a card (one of them part of a group, which stays invisible and is invoked by a button). It works once when you open the stack, but fails when you return to the card.

Open the stack; card 1 is a dummy with a button to go to card 2.
Card 2 has two browsers - one on the card, the other inside a group on the card.
They are set to sample .pdf files online.
If the pdf files show on the first go-around, please navigate to the first card and navigate back.
The browsers don't show, although you can see a blip when they load the file.

Of course you can have several browser widgets on the same card.
You can also layer and overlap them (or the enclosing group).
I use this in a sample stack for putting "controls" over a browser widget.

What you describe doesn't happen here.
So this may be a bug with a certain LC version on a certain platform.
Did you already try with 9.0.5 and/or 9.5.0?
What is your version/platform?

Tried it on 9.0.4
Same result.
Didn't try with 9.0.5 etc. I generally like to keep away from release candidates and previews.

Once the browsers vanish, I can get back one of them (the one within a group), by clicking the visibility button on the Project Browser (by hiding and showing). The other browser (not inside a group) just blips once (showing that it is loading) and it is gone.

I have figured out the issue, I think.
The group (with the browser) has to start out hidden in my program and is shown when a button is clicked. This seems to be the issue. If the card opens with the group showing, there is no problem, But when the group is hidden and is then shown, both browsers stumble.

I can script around this problem and just show the grouped browser on a separate card. I'd still like to know why this happens.